Chagas disease

Chagas disease, also called American trypanosomiasis, is a zoonotic disease, meaning one that passes from animals to people, and it can be fatal. It is caused by a parasite called Trypanosoma cruzi, which multiplies inside the body's cells.

The kissing bug carries it, and the way it spreads the infection is surprising. The insect bites, feeds, and defecates right there, next to the bite, leaving its contaminated feces on the skin. The irritation makes the person scratch, and rubbing the area pushes that material into the open wound. It gets in after the bite, when the hand carries what the insect left beside it into the wound.

Once inside, the parasite penetrates the cells nearby and changes form: it becomes an amastigote, the stage that lives inside the cell. There it multiplies by binary fission, splitting in two over and over, mostly in muscle cells and nerve tissue.